WASHINGTON — George W. Bush swore the presidential oath for a second term Thursday and issued a sweeping pledge to spread freedom “to the darkest corners of the world” and "show the meaning and promise of liberty."

"There is only one force of history that can break the reign of hatred and resentment, and expose the pretensions of tyrants, and reward the hopes of the decent and tolerant, and that is the force of human freedom," Bush said, moments after taking the oath of office.

In a speech delivered before a vast throng of fellow Americans spilling away from the steps of the Capitol, the nation's 43rd president said that advancing freedom and liberty were the oldest ideals of America. “Now it is the urgent requirement of our nation’s security, and the calling of our time,” he said in a reference to the war against terrorism.

Bush did not mention Iraq directly during his 17-minute address, but he offered an implied rebuttal to critics of his foreign policy and the war there. “Some, I know, have questioned the global appeal of liberty,” he said, “though this time in history, four decades defined by the swiftest advance of freedom ever seen, is an odd time for doubt.”

But the president — the first chief executive to take the oath of office at a time of military conflict since Richard Nixon's second term started in January 1973, near the conclusion of the Vietnam War — also said that while the United States resorted to force in Afghanistan and Iraq during his first term, the pursuit of freedom for other people "is not primarily the task of arms."

Human rights emphasizedInstead, he said, "We will encourage reform in other governments by making clear that success in our relations will require the decent treatment of their own people. America’s belief in human dignity will guide our policies, yet rights must be more than the grudging concessions of dictators; they are secured by free dissent and the participation of the governed."

Bush said he would place the nation on the side of the world’s oppressed people. “All who live in tyranny and hopelessness can know: the United States will not ignore your oppression, or excuse your oppressors. When you stand for your liberty, we will stand with you.”

While the expansion of freedom around the globe was the overriding theme of his speech — the words "freedom," "liberty" and their derivations appeared 49 times — Bush also acknowledging divisions within the country over the war in Iraq and his ambitious second-term domestic agenda.

“We have known divisions, which must be healed to move forward in great purposes, and I will strive in good faith to heal them," he said.

Extraordinarily tight securityThe weather was cold; security extraordinarily tight for the nation’s 55th inauguration, first since the terrorist attacks of Sept. 11, 2001. Sharpshooters were perched on the rooftops of buildings near specially constructed stands at the Capitol. Police stood shoulder to shoulder along the route of the inaugural parade.

Bush delivered his address moments after raising his right hand, placing his left on a family Bible used at his 2001 inauguration, and pledging to uphold the Constitution. A frail-looking Supreme Court Chief Justice William Rehnquist
, 80, who has been undergoing treatment for thyroid cancer
, administered the oath as hundreds of dignitaries, family and friends looked on.

Moments before Bush took the oath, Vice President Dick Cheney was sworn in by House Speaker Dennis Hastert.

In addition to his immediate family — wife Laura and daughters Jenna and Barbara — Bush's father and mother, former President George H.W. Bush and his wife, Barbara, attended the ceremony, as did a host of distinguished guests that included former presidents Jimmy Carter and Bill Clinton and their wives.

After the ceremony, Bush, his family, congressional leaders and the nation's political elite attended a private lunch at the Capitol.

Partisan politics in the wingsSen. John Kerry, who had hoped to be center stage Thursday, watched somberly from a seat far across the platform as President Bush took the oath of office, and he sounded a note of defiance as he looked ahead to the next four years.

“Democracy means working together for the good of our country; it also means keeping faith with your ideals, never retreating from core convictions even as you work to find common ground,” said the four-term Massachusetts senator, who narrowly lost his bid for the White House.

Other Democrats mingled with Republicans on the platform, snapping photos and shaking hands, as former President Clinton and his wife, Sen. Hillary Rodham Clinton, D-N.Y., made their way to their seats.

While civility was the public demeanor, many Democrats made it clear that once the president’s big day was over, the battle will begin anew.

House Minority Leader Nancy Pelosi of California said, “Personally, I don’t feel much like celebrating. So I’m going to mark the occasion by pledging to do everything in my power to fight the extremist Republicans' destructive agenda.”

In an e-mail to Democratic supporters, she sought donations to the Democratic Congressional Campaign Committee, to “tell President Bush that party time is over.”

California Gov. Arnold Schwarzenegger, who made a quick trip to the snow-covered capital for Inauguration Day, also weighed in. “I’m sure he has an interest, like every American, to get out of this war as quickly as possible,” Schwarzenegger said. “The key thing now is, is to really create great relationships overseas.”

Crowds, protests, security After taking the oath of office, the president and first lady traveled the 1.7-mile inaugural parade route in an armored limousine at the head of a massive motorcade, flanked by Secret Service agents. They emerged only to walk the final yards to the reviewing stand at the White House.

Up to 500,000 people lined the route to watch the nearly two-hour procession of 14 giant floats, more than 70 marching bands and marching units, and thousands of dignitaries.

The nation’s 55th inauguration celebration ran late into the night at
10 black-tie balls
. Bush began the evening at a Salute to Heroes party honoring Medal of Honor recipients.

“I can’t tell you how much confidence I have in the members of our military,” Bush told the crowd, which cheered him with “hoo-ahs!” At the next stop, the Constitution Ball, the president and his wife delighted the crowd by dancing.

Protest and pepper spraySeveral thousand protesters had gathered in designated areas of the city, and
police fired pepper spray
at one group after demonstrators threw debris and tried to break through a security fence.

Overall, however, protests were largely peaceful, and cheers from supporters drowned out those of Bush's opponents along much of the route.

Bush begins his new term with the lowest approval rating at that point of any recent two-term president — 49 percent in an Associated Press poll this month.

And while a new
NBC News/Wall Street Journal poll
shows Bush with his highest approval rating in months, it also shows that many Americans still have doubts about the war in Iraq and question whether Bush has a mandate to revamp Social Security.

NBC News' Norah O'Donnell and the Associated Press and Reuters contributed to this report.